SHALOM? What happened to America first?

On Saturday night, agents with U.S. Immigration and Customs Enforcement (ICE) followed through on Trump's threat, detaining Mahmoud Khalil, a Palestinian student activist at New York City's Columbia University, where pro-Palestinian demonstrations last year became a national lightning rod amid a debate about the Middle East conflict. Khalil led negotiations between protesters and university officials last spring, and graduated from Columbia with a master’s degree in December.

“This is the first arrest of many to come,” Trump wrote on Monday afternoon, personally taking credit for Khalil’s arrest. “We will find, apprehend, and deport these terrorist sympathizers from our country—never to return again.”

Khalil’s situation immediately drew international attention because of the reason he was detained, and because, according to his lawyer Amy Greer, he holds a green card, which allows individuals to live and work permanently in the United States.

A habeas corpus petition was filed on Khalil’s behalf challenging the legality of his arrest and detention. He got some reprieve on Monday evening, when a judge from the Southern District of New York ruled that he “shall not be removed from the United States unless and until the Court orders otherwise.”

Khalil's wife, who is eight months pregnant, is a U.S. citizen and was also threatened with arrest, according to Greer. Khalil is currently being held at the Central Louisiana ICE Processing Center in Jena, La., according to an ICE database.

Khalil’s arrest comes just days after Trump announced he would revoke $400 million in federal funding from Columbia University, accusing the school of not doing enough to prevent antisemitism on campus. To critics, the move is intended to silence political speech critical of U.S. foreign policy.

In a statement, Homeland Security spokeswoman Tricia McLaughlin said “Khalil led activities aligned to Hamas, a designated terrorist organization,” and linked his arrest to Trump’s executive order. Secretary of State Marco Rubio later confirmed on social media that the Trump Administration “will be revoking the visas and/or green cards of Hamas supporters in America so they can be deported.” A petition demanding Khalil’s release has already generated more than 1.3 million signatures or notes of support. Protests are also planned in New York City on Monday to demand his release.